Apparatus for electrical uses



Sept. 22, 1936. E. E. FRANZ APPARATUS FOR ELECTRICAL USES Filed May 10, 1934 INVENT OR 5. E. FRANZ ATTORNEY Patented Sept. 22, 1936 PATENT OFFICE APPARATUS FOR ELECTRICAL Erwin E. Franz, Craniord, N. J., assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application May 10, 1934, Serial No. 724,925

'1 Claims.

This invention relates to laminated articles and a method of and apparatus for making them,

and more particularly to laminated cores for electrical and magnetic apparatus and a method of and apparatus for assembling the cores and adjusting them in electrical apparatus.

In the manufacture of electro-magnetic apparatus particularly, such as induction coils and the like in which one or more electrical conductors are wound upon or coiled and placed upon a core of magnetic material it is often advantageous to have the core built of laminar units of magnetically highly permeable material such as certain recently discovered alloys of nickel and iron or of nickel, chromium and iron which are unusually permeable aiter proper heat treatment. Such alloys, however, are extremely sensitive and lose permeability to a marked degree when subjected to only small degrees of cold working such as bending or twisting. or even compression. In some instances cores built up of laminae of such material have been fastened together with mechanically compressive clips, or with rivets or bolts, or other analogous means which impose more orless stress upon and thereby induce some strain in the material thus tending to adversely affect the permeability.

An object of the present invention is to provide a method of and apparatus for making cores of permeable alloys and assembling them in electrical apparatus in which no stress upon or strain in the material is produced thus tending to maintain their high permeability unimpaired.

With the above and other objects in view one embodiment of the invention comprises stacking a file of core laminations together, applying a viscous adhesive substance to the congruent edges of the laminations and letting the adhesive dry. Two such assemblies of laminations which are then sufficiently coherent to be handled gently without disruption, may then be placed in position in or/and around one or more preformed coils of conductor strands with or without a supporting spool of dielectric material. A supply of adhesive-material may be placed between juxtaposed parts of the two laminated core stacks. A testing instrument may then be connected to the coiled conductors to test some electrical characteristic of the coil such as self inductance, mductive coupling between coils, or the like, which is a function of the permeability of the magnetic circuit through the two core parts. The latter may then be adjusted to a desired predetermined value by approximating or separating the two u core stacks thus altering the air gap between them. -When the desired value is attained the whole assembly is held lightly but rigidly in place until the adhesive between the core stacks dries. Thus a core is produced and assembled in electrical apparatus of accurately predetermined magnetic reluctance while preserving the magnetically sensitive material of the core from any impairment. Means are also provided to hold the core halves immovably apart while the interposed adhesive material is drying since such material ordiriarily Shrinks while setting and would tend to draw the core halves together if they were free to move thus altering the carefully made and sensitively adjusted magnetic circuit.

Other objects and features of the invention will appear from the following detailed description of one embodiment of the invention taken in connection with the accompanying drawing in which like reference numerals are applied to identical parts in the several figures and in which Fig. 1 is a perspective view of an inductance coil embodying the invention;

Fig. 2 is a view of such a coil in central longi tudinal section, the coil being held in an assembly and adjustment device; and p Fig. 3 is a broken perspective view of a c0m= pleted half core.

In the embodiment of the invention herein disclosed, an inductance coil comprises two half cores 2i and 2i of magnetic material, a spool 22 of dielectric material mounted on the cores 29,

and two conductors 23 and 24 wound on the spool.

The two half cores 25 are identically alike'in shape and are symmetrically juxtaposed in the assembled coil. Each half core comprises a plurality of flat E shaped laminae 25 punched or otherwise formed from a sheet of highly magnetically permeable alloy such as certain well known alloys of iron and nickel known generally as permalloy and containing in one case, for 40 example, 17.7% iron, 78.5% nickel and 3.8% chr0- mium. These alloys are highly sensitive to mechanical stresses and strains, especially when in their condition of maximum permeability which is attained by heat treatment. 4

The laminae 25 after being formed are heat treated to produce maximum magnetic permeability therein, the specif c alloy above mentioned being annealed at about l980 1?. for an hour and cooled slowly. The laminae are then magnetically highly permeable and so sensitive that even slight accidental cold working or jar ring will decrease the permeability by a quarter or even a third or more.

In some instances such laminae in the past have been appropriately perforated before the heat treatment and after being treated have been filed in stacks and fastened together by means of rivets passed through the perforations.

. with the present invention the block of heat It is extremely difficult, however, to fasten the rivets or other means tightly in place without some deformation of at least the two or three external laminae on each side of the stack with consequent loss'of permeability. However, in some cases it is not necessary that the laminae be strongly held together. Hence inacc'ordance treated and stacked laminae is coated on one or more peripheral faces formed by the edges of the laminae with a viscous and relatively quickdrying cement. A solution or dispersion of a cellulose product in a solvent such as acetone or trichlorethane or the like has been found satisfactory for this purpose. The cement is preferably sufliciently thick and viscous not to be drawn in between the laminae by capillary attraction, but to remain on and adherent only to the edges of the laminae.

It is found that a block of metallic laminae thus held together is sufliciently well united to be transported andmanipulated as a self coherent unit satisfactorily, especially if the adhesive coating be applied to at. least two mutually perpendicular faces of the block. Such a. block is separately illustrated in Figure 3, in which the laminations are indicated at 25 and the adhesive coating 26 is applied to three faces of the block of laminae.

In the illustrative example herein disclosed, the spool 22 and its windings 23 and 24 are assembled as a unit before being combined with the two core halves 2L. The spool consists of a central sleeve 21 on the outside of which the windings 23 and 24 are placed, spacing flanges 28, 29 and 30 which serve to confine the'windings and an internal transverse septum 3i. The sleeve 21, flanges 28, 29 and 30, and the septum 3| are integral and the whole is preferably molded from a moldable dielectric material such as hard rubber, artificial resin, cellulose acetate, or the like, although the precise nature and form and material of the spool are no.part of the invention.

With the parts as shown, the core halves are assembled with the wound spo'ol by inserting the central tongue 32 of each core half into the ends of the sleeve 21 and means are preferably provided to retain the cores in place. According to the invention this means comprises masses 33 of adhesive material like that used for thecoating 26 placed in the bottoms of the two pockets formed within the sleeve 21 by the septum 31.

There are two distinct relative adjustments of the two half cores and of the wound spool thus assembled which are of importance; the adjust ment of the air gap between the half cores to obtain a predetermined total reluctance of the magnetic circuit and theadjustment of the core with and be adjustable in position by the screw 41. The cradle has two upstanding parallel lugs 44 adapted to receive and hold the spool 22 which flts snugly between them. 1 A post 45 is secured to or integral with the rear of the base member 40 and carries a generally 0 shaped clamp 46 extending over the trough of the base. The clamp 46 is formed and proportioned to receive between its resilient ends a pair of core halves and to urge them gently together as shown.

A second adjusting screw 41 is also mounted in the base member 4|] transversely thereof and has a knurled head 48. Two opposed and coacting wedges 49 and 50 are mounted in the base member with freedom to slide transversely thereof, and are perforated'and threadedto 'coact with the screw 41 to be driven thereby. The screw 41 is oppositely threaded at its two ends and so acts to draw the wedges together when turned one way and to drive them apart when turned the other way. These wedges are so positioned and proportionedas to enter between the adjacent opposed arm ends oftwo core halves as shown.

In operation a spool 22 having windings 23,

spool with their .central arms 32 positioned in the central pockets of the spool. The spool and the two core halves thus assembled are then placed in position in the adjusting apparatus other under the urge of the spring 46 until the reluctance value of the magnetic circuit required is attained. Then by manipulation of the knurled head 42, the spool 22 with its windings 23 and 24 may be adjusted longitudinally of the core until the mutual inductance of the windings takes on its desired value.

The whole is then allowed to rest until the adhesive masses.33 are thoroughly dry and have attained a substantially final state of invariable volume and form.

During this drying or setting of the adhesive masses'33, they tend to contract anddraw the core halves together and thus tend to close the air gap between the core halves and change the adjusted value of the reluctance of the magnetic circuit. They also may shrink unequally thus tending to shift the spoolon the core as a whole which would tend to disturb the adjusted value of the mutual inductance of the windings. tendency of the adhesive to draw the core halves together is resisted by the positiveand immovable wedges interposed therebetween, and the tendencyof the adhesive to shift the spool on the cores is resisted by the positive and immovable grip of the lugs 43 and 44 on the spool. v

Thus the spool with its windings and the two core halves are held immovably in their adjusted relative positions until the adhesiveis set and has become an unchanging unifying element in the whole assembly; The finished coil is then removed from the apparatus and has and maintains the desired electromagnetic property values.

The embodiment of the invention herein dis- The' closed is illustrative merely and may be modified and departed from in many ways without departing from the spirit and scope of the inventtion as pointed out in and limitedsolely by the appended claims.

adhesive material between the windings and the core and means were provided to adjust the core halves relatively to each other and to adjust the windings on the core and to hold the core halves and the windings relatively immovable in positive fashion until the adhesive between the core halves and between the core and the'windings were permanently set, the essence of the invention would still be present. It may also be pointed out that the means such as the wedges 49 and 50 to hold the core halves apart must be positive since the tendency of the adhesive 33 in drying and setting is to shrink and draw the core halves together. Spring means instead of wedges or other positive means will not do. On

the other hand spring-means to-hold the pore halves together are sufficient although a positive means might equally wellv be used.

What is claimed is: 1. The method of manufacturing electrical apparatus which comprises juxtaposing two magnetic core members with adhesive material therebetween, adjusting the magnetic gap between the members until predetermined electrical properties are obtained, and positively holding the core members against approachto each other until the plastic adhesive material has permanently set.

2. The method of manufacturing electrical apparatus which comprises juxtaposing two mag- 40 netic core members with adhesive material therebetween, assembling therewith a third member with plastic adhesive material there, between, adjusting the magnetic gap between the core members and adjusting the po- 5 sition of the third'member relative to the core members until predetermined electrical properties are obtained and positively holding the three members against approach to each other until the plastic adhesive material has permanently set.

3.' The method of manufacturing electrical coils which consists in placing a winding on a divided core, positioning adhesive material between the ends of the core which provides an air gap between the core sections, adjusting the air gap with the adhesive material in a plastic state until predetermined electrical properties are obtained, and holding the wholepositively against the contrative efiect of the adhesive material while drying until the adhesive material has permanently set.

4.-The method of manufacturing electrical apparatus having magnetic cores of unstressed laminae construction which comprises stacking together laminae of magnetic material into a block, applying adhesive material to a surface of the block formed by the edges of a plurality of the laminae, allowing the adhesive material to permanently set, assembling'two such blocks together with a winding, positioning a second supply of adhesive material between the two blocks and between the blocks and thewinding, adjusting the relative positions of the two blocks and of the Winding untilpredetermined electrical properties are obtained, and positively holding the twoblocks and the winding in relative position against the contractive effect of the drying adhesive material until the second adhesive material has permanently set.

5. In an apparatus for assembling electrical devices having a two part core and a'-winding thereon, means to press the two parts of the core together, positive mean to force the two parts of the core apart, and means to positively adjust the position of the winding'relative to the coie parts. I

6. In an apparatus for assembling electrical apparatus having a two part core and a winding thereon, means to adjust the two parts of the core positively with respect to each other and to hold them positively in their adjusted position against approach toeach other, and means to positively adjust the winding in position with respect to the core parts and to hold the same immovably in its adjusted position.

'7. In an apparatus for assembling electrical apparatus having a two part core with adhesive material between the parts thereof, means to adjust the two parts of the core positively with respect to each other. while the adhesive material is soft and to hold the core parts positively in their adjusted position against approach to each other while the adhesive material sets.

' ERWIN E. FRANZ. 

